Picture telegraphy



EJE-440,490

Dec. 24 l 92 9.

G. M. WRIGHT ET A;

PI GTURE TELGRAPVHY 2 Sheets-Sheet Filed April 14, 1927 INVENTORS @cf 24, E929. 3. M. WRIGHT El' Afl.

PICTURE TELEGRAPHY Filed April 14; 1927 Z Sheets-Sheet i Patdnted Dec. 24, 1929 UNITED STATES GEORGE MAURICE WRIGHT, SIDNEY BERTRAM SMITH, AND NORMAN EU'STACE PATENT "OFFICE DAVIS, OF CHELMSFORD, ENGLAND, ASSIGNORS TO l AMERICA, A CORPORATION OF DELAWARE RADIO CORPORATION OF PICTURE TELEGRAPHY Application1 filed Apr1 14, 1927, Serial No. 183,631, and in Great Britain April 21, 1926.

This invention relates to picture telegraphy, and more particularly to what is someor picture while the message form itself is stationary or moving only slowly. lt will be seen that the positioning of a message form 'upon a rapidly moving part of the apparatus is likely to involve considerable dimculty, while if the apparatus has to be stopped, for the message form to be placed in position, delay will result.

4. If the. apparatus includes a source of light and a photo-electric cell or the like (as apparatus for picture telegraphy almost in.

variably does), these should be stationary.

5. In the case of a receiver, in addition to the above requirements, it is desirable that there should be some simple indication that the picture is registering properly on the sensitive form used for reception.

According to the present invention, apparatus for the telegraphic transmission and reception of pictures or the like comprises a stationary source of light, an optical system for projecting a point of light upon a message form or upon a message receiving device, and means for moving the optical system, whereby the point of light is caused to move over substantially the whole surface of the message form or message receiving device.

The invention is illustrated in the accompanying drawings in which Figures l and 2 show in schematic form two modifications in accordance therewith, while Figure 3 shows in elevation, and Figure 4: in plan, a further modification. Throughout the figures, like plarts are designated by like reference numera S- Referring rst to Figure 1, 1 1 are lines representing the boundaries of a beam of' light from an are or other suitable source. The

said light is projected axially along a tube 2,

rial, such as glass.

Light is reflected back from the image point 5 through a suitable lens arrangement 8 carried' by the tube 2v on to a mirror 9 placed transversally across the said tube, whence the tionedl tube,- and made of transparent matereected beam is diverted through a-right angle so that it is projected axially along the tube in the same direction in which the light from the original source was projected. This reected light is then focussed upon a photo# electric cell, as illustrated diagrammatically and conventionally by the numeral 35. Any well known means are provided for rotating -or oscillating the tube and also for .progressively advancing the said tube in an axial direction, so that the image point upon the message form moves over substantially the whole surface of the said message form. 'lhe lens 8, through which the light reflected from the image point passes, is concentric with and llarger than the focussing lens 4, the latterl being arrangedina protecting tube 10 passing through the former and embracing the prism so that there is no interference between the outgoing and the reflected light. 11 is a mirror for collecting the refiected light reflected from the form or device 6. It will be seen vthat the light reflected from the .message form will vary in intensity and strength with the message inscribed upon the said form, since the amount of reflected light will vary with the degree of light and shade of the message upon the said message form.

'In a modification, the tube is oscillated or rotated, while the message carrier is progressively advanced in an axial direction. Preferably the means for causing relative axial pro- 10.0

gression between the tube and the message carrier comprises a clutching device, whereby the said mechanism may be disengaged while the message form is placed in position.

Instead of using a transparent glass cylinder for the support of the message, we may alternatively use a brass or other metal supporting surface. In such a case a slot is cut in the cylinder in order to allow the light to fall on the message surface. The relative motion between message and the rotating tube is then obtained by sliding the message over the surface of the brass cylinder. By this means every part of the message successively passes the slot.

In a further modification, illustrated in Figure 2, the lens 8 through which the reflected light passes is located further along the tube than the focussing lens 4, there being provided a spherical mirror 11 whose centre is the focus point, the said mirror serving to collect the reiected light for projectio through the said lens 8. f

v The arrangements 'hereinbefore described may be rendered suitable for the reception of picture telegraphy by substituting for the message form and associated optical system for collecting the reflected light, a Kerr cell or other light modulating device, and a light sensitive receiving surface. The light from the arc lamp or other source is modulated by the Kerr cell and focussed by the prism and lens upon the sensitive receiving surface.

It will be seen that in a receiving arrangement in accordance with this invention, owing to the persistence of vision, it is possible to ascertain whether the received message is registering properly pn the form since each line traced by the focus point will be seen by the eye as a streak across the receiving surface, and it can at once be seen whether this streak is falling in the correct place on the form. rIhe arrangement of apparatus illustrated by Figs. 3 and 4 is intended to function in a manner identical to that conventionally shown by the diagrams of Figs. 1 and 2 and, to refer to Fig. 3 the screwed shaft 18a which is driven from the worm 18 of Fig. 4 is arranged at all times to carry a message form 6 longitudinally of the light systems 20 and 21 so that light, as directed through the tube 2 in the manner shown in Figs. 1 and 2, will strike the light system 20 (corresponding to 3 of Figs. 1 and 2) and be projected through the slot 30 against the message form 6 from which it is redirected as refiected light through the lens system 8 in the same manner as shown in Fig. 2 and brought to act upon the rotating reflecting system 21 (corresponding to 9 of Fig. 2). The motion of the message form 6 is continuous and is derived as above stated from the rotation of the motor 12 so that as .the light system is rotated from the worm connection 19, new portions of the picture to be transmitted will be placed continuously above the slotted p0rtion 30 of the message form 6 so as to enable the light beam entering the reflecting lens system 20 from a point to the right of 2O (looking at Fig. 4) to scan all portions of lthe picture carried by the message form. As shown in Fig. 3 there is a large bracket arm 31 carried from a pivotal mounting 32. rI`he bracket arm or yoke 31 is preferably provided With any suitable form of belt of a desired Width for holding the message tight Vagainst the message form 6, and the pivotal connection provides means whereby the bracket arm can hold the picture surface tight against the message form and yet an arrangement which can be quickly released upon beingA moved in a counter-clockwise direction (looking at Fig. 3) about 32 as a pivot and thus quickly release the picture from the message form. It is to be noted that4 Fig. 4 is shown in opposite relationship to the showing of Fig. 2 and that if Fig` 2 is turned end for end so that the light directed from the lens 4 can be assumed to direct itself toward the bottom of the page instead of toward the top of the page, as shown, the analogy between Figs. 2 and 4 Willbe at once apparent and it will be seen that the photocell to which the reflected light from the reecting system 21 is directed will be placed at the left end of the light tube 2 vof Fig. 4.

Preferably in carrying out the invention, means are provided for adjusting the phase of the receiving device so that should the streak of light referred to in the last paragraph not fall in the correct plane on the mes-v sage form, adjustments may be made. This may be effectedv by rotatably mounting the driving means, for example, a synchronous motor, in trunnions or the like and rotating the whole machine by means of suitable gearing, thereby advancing .or retarding the armature. This adjustment may be effected either by hand or automatically.

Preferably the message form or receiving surface does not occupy the whole cylindrical circumference of the message carrier (tube 7 in the figures), but embraces only an arc thereof. If desired a plurality of such message forms may be employed so that between them they occupy substantially the whole cylindrical circumference, and a corresponding plurality of machines be provided` the said machines being mechanically' or electrically geared together and the arrangement being such that the several spots of light traverse their respective arcs successively,

thereby utilizing the complete revolution. In this way a multi-Way system having two or more independent spots of light maybe obtained;

In the modification shown in Figures 3 and 4, 12 is a driving motor which is mounted upon a pedestal 13 and whose carcase may be rotated by means of a handle 14 driving a transmitted, a stationar 'entitled to all modifications that fall fairly Within its scope as deined by the following claims, wherein We claim:

1. ln a picture transmission system, a stationary source of light, a message form for supporting the picture to be transmitted, optical means or projecting the light from said source to a point on said supported picture, means for mounting said optical means within said message form, means for causing said projected light to traverse the entire message form, and means for collecting.

light reflected from said picture.

2. In a picture transmission apparatus, a message form adapted to support a picture, a stationary source of light, means for directing said light Within said message form, optical means for projecting a point of said light upon said message form, said means comprising a reecting prism and a lens, a second lens concentric with said lirst named lens, said second lens being adapted to direct reflected light from said message form, and electrical means controlled by said relected light for varying the strengthV of an electric current in proportion to the pigmentation of the picture upon said message form.

support adapted to mount a message to be source or light, means for directing sai light within said support and long gfitudinallu thereto, means for diverting said light through an angle and projecting it upon the message mounted upon said-support, means tor collecting the light reflected from said message, and means for diverting said redected light in the path substantially in a straight line with the light issuing from said source.

d. The system claimed in claim 3 ywherein a photo-electric cell is positioned in the path ot said diverted reflected light, said photoelectriccell being adapted to produce variations in an electric current in a circuit associated therewith in accordance with the light and shade of the message mounted upon said support. A

5. 'lhe system claimed in claim 3 wherein means is .provided for rotating saidy light projecting and diverting means, whereby the entire message upon said support is exposed to light from said source.

6. In a picture transmission system, a stationary source of light, a message form for supporting a picture to be transmitted, optical ineans for projecting the light from said source to a point on said supported picture, means for rotating said optical means within said message form, means for causing said projected light to traverse the entire.

message form, means for collecting light re lected from said picture and means associated with said collecting means for increasing the amount of reflected light from said picture surface reaching said collectu ing means.

7. ln a picture transmission system, a stationary source of light, a messagelform for supporting a picture to be transmitted, op tical means carried within said message form for projecting light against said message form, means for causing said projected lightv to trace successive paths transverse et said message form, means for advancing said message form with respect to said projected light whereby each successive path of projected light covers a di'erent portion ot the picture carried b said message form and means for collectmg the light redected from said message form.

8. A picture transmitting apparatus in cludinga member adapted to support a pic ture bearing sheet, a rotatable member, means mountedon said member for projecting light upon said sheet, and means for re`1 ceiving and directing the light reected from said sheet along apredetermined path.

9. A picture transmitting apparatus in cluding means for supporting a picture bearing sheet, a rotatable member, a lens mount= ed on said member for projecting light upon "i said sheet and a lens mounted on said mem- 3. ln a picture transmission apparatus, ai

ber for receiving the light r'eected trom said sheet.

10. A picture transmitting apparatus inn cluding means for supporting a picture bearing sheet, a `rotatable member, a lens mounted on said member for projecting light upon said sheet, a lens mounted on said member tor receiving the light reected from said sheet, and means mounted on said member for changing the direction or the light redected through said lens. l1. A picture transmitting apparatus im cluding a stationary support, a hollow shaft, means mounted on said shaft for projecting light toward said support and tor receiving the light redected away from said support and means arranged to direct said reflected light through said hollow shaft.

12. A. picture transmitting apparatus including a support, a hollow rotatable shaft, a lens mounted on said shaft tor projecting light toward said support, a lens on said shaft for receiving the light relected away ne Y on said member for projecting light toward l said picture bearing sheet and for receiving the light reflected away from said sheet, and

means for moving said sheet.

GEORGE MAURICE IVRIGH'I. SIDNEY IBERTRAM SMITH. NORMAN EUS'IAOE DAVIS.'

maaien 

